v ABSTRACT Optimizing airflow performance during intake valve process is the main purpose for this project. Research had using two previous works as guidance and starting point to setting and achieving targeted limit of optimized airflow, 0.0201075 m³/s. modifications on inlet valve, inlet port of intake system had been done, and original cylinder head Ex5 geometry had been used before turning into 3D modeling as to achieve objective. Analysis was done in CFD simulation and experimental using SuperFlowbench machine. This analysis also reported differentiation that occurs during both analyses around 0.045 % in average where experimental result cannot achieve targeted limit due to some realistic condition. Fabrication of intake valve and intake port also were made to do analysis on experimental based on the modify design. This being done after simulation analysis, modeling design was using to be fabricated and analyze the model on flow bench machine to verify simulating result. This analysis could be used to increase efficiency of volumetric flow rate and maximizing usage of air fuel in combustion process, which reduce emission to environment. Even though air flow have been optimized on its intake valve and port, but still intake system could be improve by considering other parts of Ex5 engine such as intake manifold.
vi ABSTRAK Pengoptimisan aliran udara masuk sewaktu melalui injap masuk proses merupakan matlamat utama projek ini. Kajian telah menggunakan dua projek yang sebelum ini sebagai panduan dan titik permulaan sebagai arah dalam mencapai target limit kadar isipadu udara, 0.0201075 m³/s. modifikasi ke atas injap dan laluan masuk bagi kemasukan system telah di jalankan dan geometri asal bagi kepala silinder Ex5 digunakan sebelum ditukarkan dalama bentuk 3D model. Analisis boleh didapati dalam CFD simulasi dan eksperimen analisis yang menggunakan mesin SuperFlowbench. Kajian turut menunjukkan perbezaan antara kedua-dua analisis yang wujud dengan perbezaan sebanyak 0.045% secara purata di mana nilai ekperimen tidak dapat mencapai sasaran limit disebabkan oleh beberapa keadaan realistik. Injap dan laluan masuk telah direka dan dihasilkan untuk eksperimen proses berdasarkan modifikasi baru rekaan. Analisis ini dapat digunakan untuk meningkatkan kadar kemasukan isi padu udara ke dalam silinder dan memaksimumkan penggunaan udara-minyak dalam proses pembakaran yang ternyata mampu mengurangkan pencemaran. Walaupun pengoptimisan telah dilakukan, namun secara keseluruhan bagi sistem kemasukan bagi enjin masih boleh di perbaiki dan dipertingkatkan dengan mengambil kira komponen lain seperti kemasukan manifold.
vii TABLE OF CONTENTS Page SUPERVISOR S DECLARATION ii STUDENT S DECLARATION iii ACKNOWLEDGEMENTS iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES x LIST OF FIGURES xi LIST OF SYMBOLS xiii LIST OF ABBREVIATIONS xiv CHAPTER 1 INTRODUCTION 1.1 Introduction 1 1.3 Problem Statement 2 1.3 Objectives 3 1.4 Scopes 3 1.5 Hypothesis 4 1.6 Methodology 4 1.7 Project Flow Chart 4 CHAPTER 2 LITERATURE REVIEW 2.1 General design of intake valve 5 2.2 General design of intake port 7 2.3 airflow condition in inlet port 9 2.4 Limitation during intake process flow 12 2.5 Review of previous work 15 2.6 Modification consideration 16
viii CHAPTER 3 DURABILITY ASSESSMENT METHODS 3.1 General methodology 20 3.2 Literature study 21 3.3 Modification of 3D modelling design 21 3.4 Boundary condition setting simulation 23 3.5 Modification 3D modelling design 21 3.6 Airflow simulation 27 3.7 Analysis simulation result 30 3.8 Fabrication design 30 3.9 Experimental using Super Flowbench machine 35 3.10 Data verification 41 CHAPTER 4 RESULTS AND DISCUSSION 4.1 Introduction 42 4.2 Simulation result 42 4.3 Refinement result 48 4.4 Fabrication product 50 4.6 Experimental result 53 4.7 Comparison experimental and simulation result 58 CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 5.1 Conclusion 61 5.2 Recommendations 62 REFERENCES 63 APPENDICES 66 A Honda EX5 specification 67 B1 Technical drawing of cylinder head 69 B2 Technical drawing of intake valve 70 B3 Technical drawing of plug 71
ix B4 Technical drawing for cylinder block 72 B5 Technical drawing of assemble design 73 C MDX 540 machine specification 75 Front view 75 Side View (Right) 75 Side View (Left) 76 Spindle 76 VPanel 77 Handy Panel 77 D Super Flowbench machine 78 Specifications 79 Flow Bench Panel 79 Panel Description 80 E1 Gant chart FYP1 81 E2 Gant chart FYP2 82 F Technical paper 83
x LIST OF TABLES Table No. Page 2.1 Advantages and disadvantages modifying intake valve design 18 2.2 Advantages and disadvantages modifying port cylinder head design 19 3.1 Modification setting on inlet valve 24 3.2 Modification setting on inlet port design 25 3.3 Data analyzing for range 1 and 2 36 4.1 Simulation result of modify design at different opening valve 43 4.2 Different types of modelling design result 44 4.3 Simulation result at maximum opening valve 48 4.4 Shown result from the testing range 1 53 4.5 Shown result from the testing range 2 54 4.6 Result of volume flow rate 58
xi LIST OF FIGURES Figure No. Page 1.1 Project flowchart 5 2.1 Original inlet valve Ex5 and in 3D modeling design 7 2.2 (a) Intake and exhaust valve and (b) intake valve design geometry 8 2.3 Differential angle and valve seat width 9 2.4 Flow pattern through the intake valve seat at different lift 11 2.5 Flow pattern trough the intake port with bias angle 12 2.6 valve shrouding 14 2.7 Result from past year integrated design valve product 17 3.1 Assemble 3D modeling of new design 23 3.2 Intake valve 23 3.3 Inlet port of cylinder head 24 3.4 Boundary condition setting 26 3.5 Generate airflow simulation operation 28 3.6 (a) Meshing cell misplaced and (b) After refinement process 29 3.7 Refinement meshing setting 29 3.8 Selection a tool to be installing 32 3.9 Register tool specification 32 3.10 Display a data V-Panel 33 3.11 Cutting material process into dimension needed 34 3.12 During fabrication process 34 3.13 SuperFlow SF-1020-SB with the adapter 35
xii 3.14 Test orifice plate 37 3.15 Setting on intake flow control 38 3.16 Flow range trend setting (a) and (b) 39 3.17 Range direction 39 3.18 Test pressure 39 3.19 Test function menu 40 3.20 Determine leakage airflow 40 4.1 Volume flow rate at 4 different types of design 45 4.2 Result for original design at 100 percent valve opening 46 4.3 Result for modified design at 100 percent valve opening 46 4.4 Decrement of simulation result after refinement process 49 4.5 Assemble of modification 3D modelling design 50 4.6 Material selection and cutting process 50 4.7 Machining process 51 4.8 Fabrication of inlet port 51 4.9 Fabrication of valve 52 4.10 Assemble of fabricate product 52 4.11 Flow rate result using range 1 55 4.12 Flow rate result using range 2 56 4.13 Average result of volume flow rate 57 4.14 Volume flow rate in 3 different types analysis 59
xiii LIST OF SYMBOLS º Degree % Percentage
xiv LIST OF ABBREVIATIONS Patm D Al CFD mm m³/s CAD 3D RPM HP CRC RFC cm IC CFM CNC OVI OVE Pressure at atmospheric condition Diameter Aluminium Computational fundamental domain Milimeter Meter cubic per second Computer-aided design Three dimensional Revolution per minute Horse power Curvature refinement criterion Refining fluid cells Centimeter Internal combustion Cubic feet minute Computer numerical controll Opening valve intake Opening valve exhaust
CHAPTER 1 INTRODUCTION 1.1 INTRODUCTION On four-stroke engine on single cylinder engine like Honda EX5, a process happened called as gas exchange process through the internal combustion engine that often informally referred to as intake, compression, combustion, and exhaust strokes. The purpose of the exhaust and inlet processes is to remove the burning gases at the end of the power stroke and admit the fresh charge for the next cycle. Increasing performance of engine contribute to the deliberation of air-fuel mixture into intake system. Internal combustion engine have similarity concept with air pump, the more air could be pump, and the more power will be produce. Performance intake air-fuel system directly related to the cylinder head. A substandard cylinder head will deliver substandard power. Air streams into the intake valves by ways of ports. The shape and size of these ports control flow pattern and velocity. These are the two critical components of port design. The optimum design will yield the highest flow (volume) of air while maintaining the highest velocity. Reducing the restriction means letting more air into the cylinders. By having more air, more fuel could be adding. The result will increase in horsepower. In order to gain power, irregularities such as casting flaws are removing and with the aid of a flow bench, the radius of valve port turns and valve seat configuration can be modifying to promote high flow efficiency. This process called porting, and can be work through hand, or via CNC machine. Basic porting does not
2 attempt to correct any design or engineering deficiencies. Interesting fact on basic porting is that in many cases, greatest performance gain per dollar spent comes upon application of basic porting procedures to a production cylinder head. Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve the quality and quantity of the gas flow. Porting the heads provides the finely detailed attention required to bring the engine to the highest level of efficiency. Unfortunately, it cost much of money, time, and professional skills to attempt best basic porting. Using simulation analysis covers this weakness of basic porting. Using computational fluid analysis to determine head porting modification is necessary because it will reduce more time and save the cost in every change of design porting. Besides that, analysis goes more on flow pattern of air fuel intake port that use fundamental CFD, CosmosFlowork a friendly user software. 1.2 PROBLEM STATEMENT Resulting from previous work, performance of airflow intake valve for fourstroke engine was increasing during its lift by modifying design of inlet valve, which is fillet radius valve. Airflow rate started to increase at 3.4mm and stopped at maximum lift, 5.3mm. [2] Even though lift is increase, airflow fixed due to choke flow position that occurs when valve is fully opening. In order to increase the performance of airflow intake port to maximum volume at its maximum lift, some modifications on head porting being done in order to increase the maximum flow rate at maximum opening through simulation and experimental analysis. Some of parameters suggested from previous work are modifying through face valve angle, seat valve and stem. One of the parameter used ahead of is by changing geometry of valve, which fillet radius. Through the changing in the fillet radius, it is proves that volume flow rate can be increased due to maximum lift where
3 performance of air flow into intake port actually increased by 0.01mm higher than the original volume flow rate. This condition continues until the choking crop up at the maximum lift. Throughout this project, new concern of modification the designs are being developed in order to get higher lift than the previous result by reaching targeted limit, in range 0.0201 m³/s volume flow rate even though it is already in maximum lift. Geometry of intake valve could be modifying to increase the flow rate air due to the limitation of opening valve at intake port. This based on the theory that higher flow rate caused on higher lift and lower pressure intake valve involved. Performance of flow air fuel for intake system is fully depend on shape and design of intake valve where a bigger space for air flow entering intake port is due to its lift. Analyze through simulation that is better will be constructed in order to achieve the best recital of airflow before it being using into real application. 1.3 OBJECTIVES Basically the main purpose in accomplishing this task are stated below i. To evaluate the air-fuel mixing process ii. To optimize the maximum flow process for intake valve maximum opening 1.4 SCOPES The scope of this project focusing on i. Literature review ii. Valve design and porting modification iii. Intake air flow simulation iv. Design modification for optimization
4 1.5 HYPOTHESIS During this project, it is expected that volume flow rate of airflow could be optimize into limit setting at maximum lift. 1.6 METHODOLOGY i. Stage 1: Literature study Make review on literature study based involving title project ii. Stage 2: Modification 3D modeling design Stating modification setting on intake valve and port design using CAD software iii. Stage 3: Simulation boundary condition setting Set up boundary condition for simulation analysis. iv. Stage 4: Simulation analysis using CFD software Simulation analysis using Cosmos Flowork software. v. Stage 5: Analysis of simulation result Analyze result from simulation. vi. Stage 6: Fabrication design Fabricate design produce from analysis. vii. Stage 7: Experimental using Super Flow Bench machine Experiment the fabricate product using Super Flowbench machine. viii. Stage 8: Data verification Analyze experimental and simulation result to verify the analysis. 1.7 PROJECT FLOW CHART Progress work and research is described in form of flow chart below. The chart contains Final year project, 1 and 2 which also have been divided due to time constraint. The task also could be referring in APPENDIX E.
5 Start Literature study Analysis previous data Cylinder head (intake system) modification No Complete model Yes Boundary condition setting Airflow simulation Data analysis Yes No Data verification Documentation End Figure 1.1: Project flowchart
6
CHAPTER 2 LITERATURE REVIEW This chapter will be discussing more on elements involved that can improved the flow pattern performance and increasing maximum volumetric flow rate due to maximum valve opening or valve lift. 2.1 GENERAL DESIGN OF INTAKE VALVE Valves come in a lot of types design with main function to control the volume of flow and pressure of fluids. Valves are use in many areas of commercial application, domestic and process application, automobiles, hydraulic presses, medical equipment and many more. Most internal combustion engine use poppet valve. The position of this valve is the top of the cylinder head. Several types of valve are used: a poppet, rotary, disc and a sleeve. The most common valve is the poppet valve. The poppet valve is inexpensive and has good sealing properties, making it such a popular choice. The following evaluation will assume poppet valves used for both the inlet and exhaust ports.
7 Tip Stem Fillet radius Face valve Figure 2.1: Original inlet valve Ex5 and in 3D modeling design Poppet Valves are using to control the flow of exhaust and intake gases in automobiles. These valves are controls by the camshaft and other devices and need to be very accurate and durable over extended use at high temperatures. Inlet valve opening (IVO) typically occurs at 15º to 25º BTC. Engine performance is relatively insensitive to this timing point. It occurs sufficiently before TC so that cylinder pressure does not dip early in the intake stroke. Inlet valve closing (IVC) falls in range 40 to 60º after BC, to provide more time for cylinder for filling under condition where cylinder pressure is below the intake manifold pressure at BC. IVC is one of factor that determines high-speed volumetric efficiency; it also affects low-speed volumetric efficiency due to backflow into the intake. [5] Mostly used in piston engines to open and close the intake and exhaust port in the cylinder head. The valve is usually a flat disk of metal with a long rod known as the valve stem out one end. The stem used to push down on the valve and open it, with a spring generally used to close the valve when the stem is not being pushing on. [11] The intake valve is usually larger than the exhaust valve. The reason is that when the intake valve is open, the only force moving air-fuel mixture into the cylinder is atmospheric pressure. [3]
8 2.2 GENERAL DESIGN OF INTAKE PORT Intake port generally related with valve shape so both could work out together in supplying the airflow. The inlet port is generally circular, nearly crosssectional area is no longer than required to achieve the desired power output. Although a circular cross section is still desirable, a rectangular or oval shape is often essential around the guide boss area. [11] (a) (b) Figure 2.2: (a) Intake and exhaust valve. Source: Heywood (1988) and (b) intake valve design geometry. Source: William and Donald (1993) The angle of valve surface at the interface with the valve seat is generally design to give minimum flow restriction as the airflow around the corner the stream lines separate from the surface and the cross section area of flow is less than the passage area. Usually valve angle of intake is 30º for give flow restriction and give more flow to the cylinder. The actual flow area to the flow passage area called valve discharge coefficient. Shape and angle of valve surface are sometimes design to
9 give special mass flow pattern to improve overall engine efficiency. Besides that, more design of two or three valve in cylinder head is to give more flow area and less flow resistance. [6] The valve seat is generally 45 º. Seat angles of 30º and 20º maybe. However, it also be selected to reduce valve seat wear. Small seat angles are indispensable in gas-fired engines. The differential angle between the valve seat and the seating ring achieves initial sealing along a line of contact, thus creating better seal of the face against the combustion chamber. Attention needed to ensure that the valve seat width is greater than the seating ring contact width. [24] Figure 2.3: Differential angle and valve seat width. Source: Richard Van Basslauysen,, 2004 Considering the flow through the intake port as a whole, the greatest loss must be downstream of the valve due to the lack of pressure recovery (or diffusion). This loss is unavoidable on intake ports due to the nature of the poppet valve. On the exhaust ports, the opposite condition exists and we are able to control the geometry down stream of the highest speed section, namely the valve seat. This
10 allows the possibility of good pressure recovery and is the reason exhaust ports flow better than intake ports of equal size do. [10] Air has mass and does not like to hug a port wall around a short-side turn. That is why purpose-built race heads have steeply down-drafted ports. However, when heads have to fit under low hoods, port angles have to come down. Low-angle ports, the air (at mid and high valve lifts) does not follows shape around the shortside turn very well. As a result, most of the air goes out of the long-side turn. This situation becomes more exaggerating when the higher the lift becomes. As a result, the streamlining of the port on the long side needs to provide for low, medium, and high lifts, while the seat approach on the short side needs only to deal with the requirements of low-lift flow. [9] 2.3 AIRFLOW CONDITION IN INLET PORT Air flows into the valves by ways of ports. The shape and size of these ports control flow and velocity. These are the two critical components of port design. The optimum design will yield the highest flow (volume) of air while maintaining the highest velocity (speed). By thinking port as a straw, when diameter is increased the flow will increase but with the same input pressure, the velocity will have to decrease. The result of flow and velocity might also be thought of as low RPM verses high RPM performance. Velocity needed at low engine speeds to produce HP but if the volume is not there at the high RPM, the engine will not achieve maximum horsepower and torque.[6] The characteristic of flows through valves is a parameter valve head and valve seat. The flow of velocity of fresh mixture in the intake manifold port and valve would give an effect to the volumetric efficiency by giving different discharge coefficient. In inlet valve, the discharge coefficient based on valve curtain area is discontinuous function of the valve lift or diameter ratio. If the lift is low the discharge coefficient is higher and will decrease when it lift was in intermediate but it will increase back when the lift is higher and it was because the flow separates from the inner edge of the valve seat. [2]
11 The lift and the discharge coefficient both vary with the crank angle. The discharge coefficient is determined experimentally. This coefficient accounts for the real gas flow effects. The discharge coefficient decreases slightly with lift since the jet fills less of the reference curtain area as it transforms from an attached jet to a separated free jet. [2] So the performance of inlet valve assembly is influencing by the factor of, valve seat angle and fillet radius. For seat angel it will affect the discharge coefficient in the low lift regime the rounding the upstream corner of valve seat is to reduce the tendency of flow to break away. This entire factor is to generate a rotational motion inside the engine cylinder during induction process. [9] (a) (b) (c) Figure 2.4: (a), (b), and (c) flow pattern through the intake valve seat at different lift. Source: David Vizard, (2008) When air flows towards the valve seat axis, the air is having a flow pattern, called swirl motion when passing face valve and seat angle. Swirl defined as the directional effect imparted to the inflowing gas by the shape of the inlet port or its angle of entry into the combustion chamber. Swirl assists eventual combustion by causing the mixture to be mixing and homogenously distributed in the cylinder. At the end of every exhaust cycle, there always a certain amount of exhaust gas that left unscavenges in the cylinder. If this exhaust gas allowed to be collecting into a pocket, it will retard the ignition flame travel, even preventing quite an amount of the fuel or air mixture from burning. [5]
12 Swirl generation significantly reduces the valve and port flow coefficient. Changes in seat width affect the Lv/Dv at which the shifts in flow regimes. Cd increases as seat width decreases. While seat angle, affect discharge coefficient in the low-lift regimes. Rounding the upstream corner of the valve seat reduces the tendency of the flow remains attached; increasing Reynolds number decreases the discharge coefficients. [5] By having shrouded intake valve during intake system, swirl generations are developing well in the cylinder and this result with higher swirl ratio rather than unshrouded valves. [27] Good swirl will prevent this pocket of exhaust gas from forming by evenly mixing the fresh mixture coming into cylinder with unscavenges exhaust gas. All the time this action is taking place, the fuel droplets broken down into smaller more readily combustible particles and charge temperatures are being even out. With hot and cold pockets, minimized combustion is more complete, so power automatically rises. This also with less potential for violent combustion from hot spots or hot gas pockets, the way may be opened to run a little more spark advance or a few points higher compression ratio. This could add power, particularly in the midrange and widen the engine s effective power band. [9] Figure 2.5: Flow pattern trough the intake port with bias angle. Source: David Vizard, (2008)
13 Figure 2.4 above explaining how bias angle of porting influencing flow pattern passing through intake port. By creating some biases on the port, it causing the flow "windows towards the center of cylinder which helps to generate swirl motion during intake system process at high velocity. Generally, the engine manufacturer offsetting the port from the valve centre creates swirl. Any tendency of the port to curve and produce swirl should be encouraged because port straightening reduces swirl, causing poor mixture distribution, with poor combustion being the result. [9] 2.4 LIMITATION DURING INTAKE PROCESS FLOW Flow moves through a valve due to differences between upstream and downstream pressure called pressure drop. If piping size is identical both upstream and downstream from valve and velocity is consistent, valve must reduce fluid pressure to create flow by way frictional losses. A portion of valve s frictional losses attributed to friction between the fluid and valve wall. [11] Many valves are designed to allow a portion of valve to be narrow than the piping so they can easily provide this restriction within body. [11] 2.4.1 Valve shrouding